Driving member for electrodynamic loud speakers



Nov. 12, 1935. A. T. VAN URK ET AL 2,020,814

DRIVING MEMBER FOR ELECTRODYNAMIC LOUD SPEAKERS Filed Jan. 25, 1930 M K R U M E RVK N m? R N w O D T Vm M m m NR7 F. AG B Patented Nov. 12, 1935 DRIVING MEMBER FOR ELECTRODYNAMIC LOUD SPEAKERS Arend Thomas van Urk and Gerrit Peusken, Eindhoven, Netherlands, assignors to Radio Corporation of America, a corporation of Delaware Application January 25, 1930, Serial No. 423,316 In the Netherlands March 2, 1929 Cal 1 Claim.

This invention relates to loud speakers. More particularly it relates to cylindrical driving members for the dynamic or moving coil type of loud speakers. With electro-dynamic telephones or loud-speakers it is important that the moving part has the lightest possible construction. In most cases the moving part is constituted by a hollow cylinder having windings arranged on it, and by a vibrating member attached to the said cylinder. No matter what shape the vibrating member has, either flat or conical, its attachment to the cylinder always entails technical diificulties.

According to the invention, the hollow cylinder is made of paper or. textile fabric impregnated with a phenol condensation product and is provided with a flanged edge. A flanged edge is particularly useful because the vibrating member can very easily be attached thereto. Providing a hollow cylinder with such an edge affords no technical difficulties when the cylinder is made of paper or textile fabric impregnated as above.

As above stated the vibrating member is attached to the hollow cylinder by means of a flanged edge. If this attachment is effected by gluing, it is advisable to provide between the edge of the cylinder and the vibrating member a layer of supple textile fabric, for example flannel, to which both the cylinder and the vibrating memher are attached by gluing.

The invention will be more clearly understood by referring to the accompanying drawing which represents, by way of example, an embodiment of the invention. In this drawing:

Fig. 1 represents a hollow cylinder according to the invention,

Fig. 2 shows a vibrating member attached to a cylinder according to Figure 1.

Referring to Figure 1, a hollow cylinder l0 made of textile fabric impregnated with a phenol condensation product, is provided with a flanged edge H.

A hollow cylinder can be manufactured from textile fabric in a particularly simple manner because in commerce tubular fabric is obtainable which, cut to length, is extremely suitable for use as filling substance for the phenol condensation product to press therefrom a hollow cylinder as represented in Figure 1. On the cylinder are provided wire windings l2 and, in addition, shoe eyelets l3 and M to which the ends of the windings are secured. In order to ensure a satisfactory fixation of the wire in the eyelets, leather or flannel is provided between the bent edge of the eyelet and the wall of the cylinder.

Figure 2 shows the manner in which the cylinder is attached to the vibrating member 15. The attachment is effected with the interposition of a layer iii of supple fabric to which both the cylinder and the vibrating member are secured by gluing.

What is claimed is,

In telephonic apparatus of the character described, the combination with a conical dia phragm of large diameter, of a coil form, a'voice coil on said form, means for securing said form to said diaphragm comprising a conical flange engaging said diaphragm, a lead from said coil, and an anchorage for said lead comprising means securing it to said coil form between said coil and the adjacent limits of said diaphragm and said flange, said lead extending flexibility to the external circuit from said anchorage which partakes of vibrations equal in amplitude to those of 35 said coil.

AREND THOMAS VAN URK. GERRIT PEUSKEN. 

